Wordnet 3.0
NOUN (1)
1.
(statistics) any of three points that divide an ordered distribution into four parts each containing one quarter of the scores;
The Collaborative International Dictionary of English v.0.48:
Quartile \Quar"tile\, n. [F. quartile aspect, fr. L. quartus the
fourth. See Quart.] (Astrol.)
Same as Quadrate.
[1913 Webster]
WordNet (r) 3.0 (2006):
quartile
n 1: (statistics) any of three points that divide an ordered
distribution into four parts each containing one quarter of
the scores